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 “We performed UV measurement at the pilot seats inside a general
aviation plane,” measuring the cosmic radiation coming through the
windshield, said Dr. Martina Sanlorenzo who coauthored the new
research letter.
Sanlorenzo, of the dermatology department at Mount Zion Cancer
Research Center at the University of California, San Francisco, and
her team recently published an analysis of past research concluding
that pilots and cabin crew have approximately twice the incidence of
melanoma compared to the general population (see Reuters Health
article of September 14, 2014 here: http://reut.rs/1qtoT5a).
“Our meta-analysis showed an increased risk of melanoma in cabin
crew too,” including flight attendants, Sanlorenzo said. “However,
the role of UV radiation in melanoma risk could be more important
for pilots, who are seated in the cockpits for most of the time, and
therefore have a greater exposure.”
For the new study, the researchers placed UV index meters in the
pilot seat of a small turboprop light business and utility airplane
with six passenger seats and a plastic windshield.
They took radiation measurements at ground level and at regular
altitude increments in flight, and took readings in two locations,
San Jose, California and Las Vegas, Nevada.
Then they took the same UV measurements inside a tanning bed.
According to their measurements, published in JAMA Dermatology, the
aircraft windshield blocked UV-B but not UV-A radiation.
UV-A is the most abundant source of solar radiation at the earth's
surface and penetrates beyond the top layer of human skin,
increasing the risk for skin cancer, according to the Centers for
Disease Control and Prevention. UV-B can cause some forms of skin
cancer as well, but does not penetrate the skin as deeply.
The researchers calculated that 56 minutes in the pilot’s seat of
the plane at 30,000 feet resulted in the same carcinogenic-effective
dose of UV-A radiation as a 20-minute tanning session.
“Pilots and cabin crew should be aware of the higher risk of
melanoma,” Sanlorenzo said. “They should know that windshields are
not enough to protect their work environment from UV radiation.”
Aircraft windshields should be improved to block more UV-A
radiation, she said.
“We strongly recommend the use of sunscreens and periodical skin
check examinations for pilots and cabin crew,” she added.
There is great variation in how much radiation exposure pilots will
have, depending on altitude, latitude, cloud cover, time of year and
other factors, said Hajo Zeeb, head of the prevention and evaluation
department at Leibniz Institute for Prevention Research and
Epidemiology in Bremen, Germany.
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Zeeb, who was not involved in the new research, has studied flight
crew radiation exposure in the past.
There is less exposure in the passenger area of the plane and no
exposure at night, he said.
“This is one small study, and I guess more will follow to see how
different window types allow UV-A transmission, and what would be
the best ways to also block UV-A more efficiently,” Zeeb told
Reuters Health by email. “Pilots should be made aware of the
increased melanoma risk in their professional group, but the link to
UV-A transmitted through windows is far from clear as it currently
stands.”
There could be other explanations for the increased rate of melanoma
among pilots.
“It is true, that pilots have increased incidence of skin cancer,”
said Katja Koto, a researcher at STUK Radiation and Nuclear Safety
Authority in Finland.
If it were due to the UV-exposure in cockpit, the excess would
probably be on the face and lower arm area, she said.
“Also cabin crew have increased incidence of skin cancer but there
is no UV-exposure in the cabin,” Koto told Reuters Health by email.
“These facts might support the idea that pilots and cabin crew are
exposed to excess amount of UV on their free time, which causes the
excesses of their skin cancer.”
A study of Nordic airline pilots found very similar incidence rates
of melanoma of the head and neck, limbs and trunk, said Dr. P.H.
Gaël Hammer, an epidemiologist at the Laboratoire National de Santé
in Luxembourg.
“And since the trunk is usually covered and well protected in the
cockpit, this suggests that exposures outside the cockpit are the
most likely cause of these cancers,” Hammer said.
SOURCE: http://bit.ly/1whPKo2 JAMA Dermatology, online December 17,
2014.
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